Electric switch



Sept. 10, 1929. G. BRUHLMANN ELECTRIC SWITCH Filed May 9, 1927 fatentedSept. 10, 1929 UNITED STATES PATENT OFFICE.

GESELLSCHAFT BROWN BOVERI & GIE., COMPANY OF SWITZERLAND.

ELECTRIC Application filed May 9, 1927, Serial No.

This invention relates to electric switches of the knife or similartypes used for the connection of current carrying conductors.

The object of the invention is the provision of a switch of this typeconstructed in such fashion as to use the electrodynamic influences ofthe current to hold the switch closed, as in the event of a heavy flowor surge of current, and maintain the desired insulation of theterminals from the mounting which supports the switch, without involvingthe use of insulators of undesirable height or size.

Another object is the provision of a swltch having these attributeswhich is of simple construction, reliable in performance, andsusceptible of manufacture at low cost.

Other and further objects of the invention will be pointed out orindicated hereinafter, or will be apparent to one skilled in the artupon an understanding of the invention or its employment in practice.

In the accompanying drawing forming a part of this specification, Iillustrate one embodiment of the invention, but it is to be understoodthat this is presented simply by way of example, and the scope of theinvention, as indicated in the appended claims, is not to be construedas limited simply to this particular construction or the detailsthereof.

In said drawing,

Fig. 1 is a side elevational view of a switch embodying the invention;and

Fig. 2 is a sectional View on line 22 of Fi 1.

T arious expedients have been resorted to for preventing theunintentional opening of connecting switches incident to the passage ofheavy or suddenly increased currents. In some instances catches havebeen designed for this purpose, but these are likely to interfere withthe operation of the switch, and to prove unreliable. Variousarrangements of holding clips and the switch blade have been devised tohold the latter closed under the electrodynamic forces of the current,but these have involved either bringing the terminals or the switchblade closer to the support from which it is insulated, or the OE BADEN,SVJITZER-LAND, A JOINT-STOCK SWITCH.

189,897, and in Germany June 4, 1926.

lengthening of the insulators in order to maintain the proper clearanceto prevent flash-overs. The present invention provides in a very simpleconstruction an arrangement whereby the electrodynamic forces of thecurrent may be availed of to the purpose indicated without involvingeither a. decrease in the spacing of the switch terminals and lads fromthe support or the use of insulators of undesirable height or size. Thenature of the invention may be'ascertained from the embodimentillustrated, wherein the reference numeral 10 designates the panel orsupport on which the switch base 11 is mounted. The switch base carriesthe insulators 12, upon which are mounted the switch terminals 14 and15, to the latter of which the switch 16 is pivoted at 17 The terminal14; has the clip portion 14? to receive the blade and the binding arm14* for connection of the conductor 18. The ter1ninal member is soconstructed that the portion which receives and retains the blade isbetween the binding portion and the insulator. The terminal member 15may be similarly connected with the pivot 17 between an extended bindingportion and the insulator, although it also may be formed with thebinding portion concentric with the pivot or substantially on a linewith the switch blade when the latter is in closed position.

When an electric current is passed through a conductor in the form ofaloop, electrodynamic forces are developed which tend to expand the loopor increase the area enclosed within it. This eifect is availed of bythe present construction to hold the switch closed, as the free end ofthe switch and the terminal member with which it contacts, occupy asalient position in the course taken by the current, the bottom of theterminal clip being at the outer side of the salient. Consequently, theelectrodynamic forces developed upon the movable blade by the flow ofcurrent have the effect of forcing the free end of the blade into itsseat rather than out. Since the terminal members and the switch bladeare positioned entirely beyond the ends of the insulators, all current-Camden and State of New carrying parts are spaced the full length of theinsulators from the base and support, and consequently the insulatorsneed not exceed in len h the actual distance requisite to preventashing-over bet-ween the current carrying members and the switchsupport. Accordingly, it Will be seen, the construction, while verysimple, is very effective in attaining the result desired, withinsulators of minimum size.

What I claim is:

1. In an electric switch, the combination with an insulator, of aterminal member mounted thereon comprising a seat portion and a portionfor connection to a line, said seat portion disposedbetween saidlast-mentioned portion and the insulator, and a movable switch memberclosing on the seat portion with a movement toward the insulator.

2. In electrical apparatus, spaced insulators, a supporting basetherefor, terminal current-conducting elements carried by the respectiveouter ends of said insulators and extending axially with respect to thelatter and thence laterally outwardly in opposite directions therefrom,and a switch member supported for movement into and out of contactingrelation with one of said elements to complete or break said path andarranged to complete such ath by a movement in substantially thedirection of electrodynamic forces resultant to current flow in saidpath.

3. In switch apparatus, a suporting insulator, a switch member supportedfor movement into and out of circuit-closing position and arranged fordisposition when in such position with one of its ends adjacent to andoverhanging an end portion of said insulator and with its longitudinalaxis substantially perpendicularly disposed with respect to thelongitudinal axis of said insulator, a terminal switch elementcomplementary to said end of said member and disposed for contactingengagement therewith when said member is in circuit-closing position,said element being afiixed to said end portion of said insulator andextending outwardly therefrom in a direction substantially coincidentwith the longitudinal axis of said insulator, the extended portion ofsaid element extending outwardly beyond the outer edge of said member anappreciable distance when said member is in circuit-closing position,and a conductor connected to the extended portion of said element.

In testimony whereof I have hereunto subscribed my name this 3rd day ofMay, A. D. 1927, at Camden, in the county of Jersey. GOTTFRIEDBRUHLMANN.

